WebGL: GL_RGB emulation for IOSurface backed textures. [For reference only]

gpu/command_buffer/service/framebuffer_manager.cc

Index: gpu/command_buffer/service/framebuffer_manager.cc
diff --git a/gpu/command_buffer/service/framebuffer_manager.cc b/gpu/command_buffer/service/framebuffer_manager.cc
index ccd593aac225d52313867ba0472f7b9312fd0adc..7b471e2a7ef7978022f7e9d6d5997175f1bce30e 100644
--- a/gpu/command_buffer/service/framebuffer_manager.cc
+++ b/gpu/command_buffer/service/framebuffer_manager.cc
@@ -129,6 +129,10 @@ class RenderbufferAttachment
     return false;
   }
 
+  bool EmulatingRGB() const override { return false; }
+  bool Initialized() const override { return true; }
+  void SetInitialized(bool initialized) override {}
+
  protected:
   ~RenderbufferAttachment() override {}
 
@@ -141,15 +145,17 @@ class RenderbufferAttachment
 class TextureAttachment
     : public Framebuffer::Attachment {
  public:
-  TextureAttachment(
-      TextureRef* texture_ref, GLenum target, GLint level,
-      GLsizei samples, GLint layer)
+  TextureAttachment(TextureRef* texture_ref,
+                    GLenum target,
+                    GLint level,
+                    GLsizei samples,
+                    GLint layer)
       : texture_ref_(texture_ref),
         target_(target),
         level_(level),
         samples_(samples),
-        layer_(layer) {
-  }
+        layer_(layer),
+        initialized_(false) {}
 
   GLsizei width() const override {
     GLsizei temp_width = 0;
@@ -250,6 +256,8 @@ class TextureAttachment
     DCHECK_NE(0u, need);
     uint32_t have = GLES2Util::GetChannelsForFormat(internal_format);
 
+    have |= EmulatingRGB() ? GLES2Util::ChannelBits::kAlpha : 0;
+
     // Workaround for NVIDIA drivers that incorrectly expose these formats as
     // renderable:
     if (internal_format == GL_LUMINANCE || internal_format == GL_ALPHA ||
@@ -277,6 +285,13 @@ class TextureAttachment
     return texture == texture_ref_.get() && level == level_;
   }
 
+  bool EmulatingRGB() const override {
+    return texture_ref_->texture()->EmulatingRGB();
+  }
+
+  bool Initialized() const override { return initialized_; }
+  void SetInitialized(bool initialized) override { initialized_ = initialized; }
+
  protected:
   ~TextureAttachment() override {}
 
@@ -286,6 +301,7 @@ class TextureAttachment
   GLint level_;
   GLsizei samples_;
   GLint layer_;
+  bool initialized_;
 
   DISALLOW_COPY_AND_ASSIGN(TextureAttachment);
 };
@@ -400,6 +416,40 @@ bool Framebuffer::HasUnclearedColorAttachments() const {
   return false;
 }
 
+bool Framebuffer::HasUninitializedDrawBuffers() const {
+  for (uint32_t i = 0; i < manager_->max_draw_buffers_; ++i) {
+    if (draw_buffers_[i] != GL_NONE) {
+      const Attachment* attachment = GetAttachment(draw_buffers_[i]);
+      if (!attachment)
+        continue;
+      if (!attachment->EmulatingRGB())
+        continue;
+      if (attachment->Initialized())
+        continue;
+      return true;
+    }
+  }
+  return false;
+}
+
+void Framebuffer::SetDrawBuffersAsInitialized() {
+  for (uint32_t i = 0; i < manager_->max_draw_buffers_; ++i) {
+    if (draw_buffers_[i] != GL_NONE) {
+      AttachmentMap::iterator it = attachments_.find(draw_buffers_[i]);
+      if (it == attachments_.end())
+        continue;
+      Attachment* attachment = it->second.get();
+      if (!attachment)
+        continue;
+      if (!attachment->EmulatingRGB())
+        continue;
+      if (attachment->Initialized())
+        continue;
+      attachment->SetInitialized(true);
+    }
+  }
+}
+
 bool Framebuffer::HasUnclearedIntRenderbufferAttachments() const {
   for (AttachmentMap::const_iterator it = attachments_.begin();
        it != attachments_.end(); ++it) {
@@ -537,6 +587,16 @@ GLenum Framebuffer::GetReadBufferInternalFormat() const {
     return 0;
   }
   const Attachment* attachment = it->second.get();
+  if (attachment->EmulatingRGB()) {
+    switch (attachment->internal_format()) {
+      case GL_RGBA:
+        return GL_RGB;
+      case GL_BGRA_EXT:
+        return GL_BGR_EXT;
+      default:
+        break;
+    }
+  }
   return attachment->internal_format();
 }
 
@@ -662,6 +722,8 @@ bool Framebuffer::HasAlphaMRT() const {
       const Attachment* attachment = GetAttachment(draw_buffers_[i]);
       if (!attachment)
         continue;
+      if (attachment->EmulatingRGB())
+        return false;
       if ((GLES2Util::GetChannelsForFormat(
                attachment->internal_format()) & 0x0008) != 0)
         return true;
@@ -670,6 +732,19 @@ bool Framebuffer::HasAlphaMRT() const {
   return false;
 }
 
+bool Framebuffer::EmulatingRGB() const {
+  for (uint32_t i = 0; i < manager_->max_draw_buffers_; ++i) {
+    if (draw_buffers_[i] != GL_NONE) {
+      const Attachment* attachment = GetAttachment(draw_buffers_[i]);
+      if (!attachment)
+        continue;
+      if (attachment->EmulatingRGB())
+        return true;
+    }
+  }
+  return false;
+}
+
 bool Framebuffer::HasSameInternalFormatsMRT() const {
   GLenum internal_format = 0;
   for (uint32_t i = 0; i < manager_->max_draw_buffers_; ++i) {